Hygrometer for regulating humidifying and heating systems.



PATBNTED mm 11. 19:17.

8. W. ORAMBR.- HYGROMBTER FOR RBGULATIN G HUMIDIPYING AND HEATING SYSTEMS.

Arrmourox 2mm us. 0.1009.

3 SHEETS-SHEET 2.

piiuccae:

PATENTED- JUNE 11, 1901.

S. W. GRAMBB. HYGROMBTBR FOR EBGUL ATING HUMIDIFYING AND HEATING SYSTEMS.

.LPYLIOATIOI TILED HAB- 9.1906.

8 SHEETS-BEES? 8.

save a! wihuma UNITED STATES PATENT OFFICE.

s'ruinr W-. CRAMER, OF CHARLOTTE, NORTH CAROLINA. nveaommn FOR nreuunme uummrvme AND HEATING svsrrms To all whom it may cancer-m.-

Be it known that I, STUART W. CRAMER, a

citizen of the United States, residing at .of the atmos here automatically in a factory or other bui ding and iniseparate compartmometers res actively.

ments thereof. I

The invention consists of certain improvements in construction on the device shown in my Patent 811,383, hearing date of January 30th, 1906, which will be fully disclosed in the following specification and claims.

In the accompanying drawings, which form part of this specificationt-Figure 1 represents a front elevation of an apparatus embodying my invention. Fig. 2 represents a like view of a modification of the same. Fig. 3 a diagrammatic view of the electrical conductors shown in Fig. 1. Fig.- 4 a like view of the electrical conductors shown in Fig. 2. Fig. 5 a front elevation of another modification of the a paratus, and Fig 6 adiagrammatic view 0 the electrical conduc tors shown iuFig. 5.

Reference being bad to the drawin s and the designating characters thereon, t, e numeral 1 indicates a. dry-bulb thermometer, 2 a wet-bulb thermometer, 3 and 4 indicate the columns of mercury contained in said ther- 5 and 6 int icate wires connected with the I tubes of the thermometers; extending either through the tubes, or at least through that part of the tubes which is required for indicating punposes. As shown in the drawings the wires 5 and 6 extend through the tubes, emerging from them at the points 8, 10, 9 and ll res ectively.

M. P and .Q' represent tenninbls at tached to the board or support 12, on which the thermometers are also mounted. I

The manner in which the thermometers are connected together, is by what is well knownin the electrical industry as the Whea'tstone Specification of Letters Patent.

Application filed larch 9. 1906. flerial Ho. 805,189.

bridge, it will sufiice for the purpose of Patented June 11, 1907.

this description therefore, to simply state that a Wheatstone bridge is a device used for the measurement of resistances, so called because the balance between the resistances to be measured is indicated by the'absence of a current in a certain wire forming the bridge or connection between two points of the a paratus. diagrammaticall; how the principle of the Fig. 3 illustrates Wheatstone bridge? is applied to my invent-ion.

Referring specifically to Figs. 1, 2 and 3 D of the bridge, and the resistance of the wet-bulb thermometer 2 corresponds to the arm B of the bridge, the wires through the thermometers are'connected in series .to two fixed resistances A and C forming the other arms of the bridge. The source of electrical energy 13 is connected to the circuit at the two points P and Q. The electric indicator I, (in this case a relay adapted to make and break an electric circuit) is connected across the circuit at the two points M and N. It is thus seen that if the ratio of resistance C, to the resistance D be equal to the ratio between the resistance A andthe resistance B, then there will be no current through the indicator between M and N. In the construction of the instrument such a ratio is rovided for, so that when the electrical alance is maintained there is no;

current through the indicator or relay. When the rise or fall of the column of mercury in either the wet or dry-bulb thermometer takes lace however, the balance. in the bridge is disturbed and a current flows through the indicator or relay causing it to make and break an electric circuit, as the case ma be.

In the diagram shown in Figs. 3 an 4, I

have chosen to' illustrate the resistance of the thermometers by heavy straight lines, and

to illustrate the changes in those resistances by arrow points, this being the customarg way for indicating variable resistances.

have shown these thermometer resistances t a seam respond to a fixed depression of the wet-bulb thermometer. Whereas, as a matter of fact the fixed depression of the wet-bulb thermometer is not all that is desired, a variable de ression of said thermometer must be provi ed for. This is accomplished by introducing a shunt d, around one of the thermometers so that the total resistance in D, varies according to any predetermined scale and consists of the total resistance of the shunt d, and the variable resistance of the thermometer due to atmospheric changes. This shunt d, is shown in Figs. 2, 4, 5 and 6. It will thus be seen that any predetermined scale of deression of the wet-bulb thermometer can lie provided for in the construction of the instrument.

Fig. 5 shows a modified form of the a paratus, using a straight tube of the usua form for the dry-bulb thermometer, and for the wet-bulb thermometer a bent tube of the form known to the trade as a Sixe? thermometer. Fig. 6, shows a diagrammatic illustration of thismodified form. It will be observed that one of the fixed resistances A is cut out and that the resistance of the wet-bulb thermometer is divided, 9. part of it being substituted for the fixed resistance A shown in Figs. 3 and 4. The object of this construction is to magnify the sensitivenass of the apparatus b oub the variation of resistance for eac degree c anged in temperature.

It is obvious that there are many minor modifications of the Wheatstone bridge or "balance method of connecting thermometers by which these may be accomplished. I do not, thereforelimit myself to any particular method of connect1ons, as my invention relates broadly to actuating indicating means b the disturbances of a prearranged scale 0 balanced resistances of the thermometers. 5

It is well known that there are other types of means for indicating temperature and humidity than the glass tube type of -ther-- mometer, and it is obvious that such other types may be connected up to mdrcateaccording to a predetermme scale variations in the humidity by the disturbance of the electrical balance of Wheatstone bridge connections. I do not, therefore, limit myself to any particular type. of thermometer, but, as stated above, that m intention includes any type of means for mdicat' temperatureand humidity by the disturbance of an electrical balance arranged according to a predetermined scale.

Having thus fully described my Invention, whatIclair'n is I 1. The. combination with a source of electrical energy, of means f or indicating tem rature'and means for mdzcatmg humi 'ty, each of the means being adapted to complete an electric circuit, electrical conductors con- .source of electrical ene meeting said source of electrical ene with each 0 said means, and means for in icating a predetermined relationshi between said indicating means by electrics ly balancing the resistances of said indicating means.

2. The combination with a source of electrical energy, of a dry-bulb thermometer and a wet-bulb thermometer, each of said thermometers being adapted to complete an electric circuit, electrical conductors connecting each of said thermometers in circuit with resistance to form the arms of an electric bridge, electrical conductors connectin said source of electrical energy to the arms 0 said electric bridge, and means forindicating relative changes in the temperatures as shown by the two thermometers, said means consisting of an electric indicator suitably connected between said arms of said electric bridge.

, 3. The combination with a source of electrical energy, of means for indicating ture and means for indicatin humidity, each of said means bein adapter? electric circuit, 2:. ed resistance, an electric indicator, and electrical conductors connecting up the said indicating means with said source of electrical energy and said resistance and said electric indicator, said connections including a Wheatstone bridge, in which the electric indicator consists of a relay adapted to make and break an electric circmt.

4. A hygrometer comprising .a dry bulb thermometer and a wet bulb thermometer roe.

electrically connected; in combination with a. source oi-electricai energy, and means for indicating differences in resistances of said thermometers according to a predetermined scale.

5. The combination with. a source of electrical energy, of two thermometers, one for indicating vtem erature and the other for intemperato complete an dicating humi 'ty, each of said thermometers being adapted to complete an electric circuit,

separate electrical conductors connect said source of electrical ene with each 0 said thermometers and eac thermometer with the other, one of. said conductors conta' an electro-magnetic device.

6. he combination with a source of electrical energy, of a dry-bulb thermometer and a wet-bulb thermometer, each of said thermometers being adapted to complete an electric circuit, separate electrical conductors connecting said source of electrical ener with each of said thermometers and eac thermometer with the other, one of the conductors containing" an electroem retro device.

7. The combination i h a source of electrical energy, of means for indicating temperature, and means for indicating humidity, variations in the indications of each of the means being ads ted to disturb an electrical balance, electric conductors connecti said each 0 the said means, and means or indicating a preating the electro-magnetic device, adapted to 1 determined relationship between said indicating means by said disturbance of the electrical balance.

8. A source of electrical energy, two ther mometers, each of said thermometers being adapted to complete an electric circuit, an

electro-magnetic device which in its normal Eosition indicates a predetermined scale of innidity at different temperatures, electrical conductors connecting said source of electrical energy, said thermometers and said electro-magnetic device; and means for sctumidity.

In testimony whereof I affix my signature, :0 in presence of two witnesses.

Witnesses:

'STUART W. CRAMER.

J. H. Mums, A. Booznn. 

